Pertussigen (pertussis toxin) (Ptx) is the toxin from Bordetella pertussis responsible for most of the biological activities known for pertussis vaccines. In nanogram doses Ptx enhances production of IgE class of antibodies, promoted induction of experimental allergic encephalomyelitis, enhances delayed type of hypersensitivity and increases inflammation caused by immunological reaction. Ptx also increases production of insulin, increases susceptibility to histamine and other vasoactive substances, induced lymphocytosis and has many other actions of interest. Our main aims are to elucidate the mode of action of Ptx and to develop a non-toxic effective vaccine for whooping cough. Ptx is composed of five peptides (S-1, S-2, S-3, S-4, and S-5) of which the S-1 is known to have an ADP-ribosyl transferase activity. Little is known about the function of the other subunits. Our efforts this year have been channeled toward the development of specific monoclonal reagents to detect each of these subunits. We now have specific monoclonals for S-1, S-2 and S-4. With these reagents, it will be possible to study the role each peptide plays in the biological activities of Ptx. Since Ptx is most likely the main protective antigen in pertussis vaccine, we are investigating the possibility of developing by genetic engineering techniques a Ptx molecule that lacks toxicity but still can protect against pertussis. In collaboration with Dr. Elmer L. Becker of the University of Connecticut, we have shown that Ptx inhibits neutrophil granule enzyme secretion and the chemotactic response to formylmethionyl-leucyl-phenylalanine (fMet-Leu-Phe).